Deodorized polyolefins and process for the preparation thereof

ABSTRACT

Purified polyolefins prepared by deactivating Ziegler type catalyst residue contained in polyolefins not purified by use of alkylene oxide and having off-odor are mixed for deodorization with 0.001 to 0.5% by weight of at least one deodorizer selected from the compounds having the following formulas (1) to (6): 
     
         Al.sub.x Si.sub.y (OH).sub.3x+4y.nH.sub.2 O                (1) 
    
     
         Mg.sub.x (OH).sub.2y-2x (CO.sub.3).sub.y.nH.sub.2 O        (2) 
    
     
         Mg.sub.x Ca.sub.y (CO.sub.3).sub.2x+2y/2.nH.sub.2 O        (3) 
    
     
         M.sub.x Si.sub.y (OH).sub.2x+4y.nH.sub.2 O                 (4) 
    
     
         M.sub.x Al.sub.y Si.sub.z (OH).sub.2x+3y+4z.nH.sub.2 O     (5) 
    
     
         M.sub.x Al.sub.y (OH).sub.2x+3y-2z (A).nH.sub.2 O          (6) 
    
     where M represents Mg or Ca; A represents CO 3 , HPO 4  or SO 4  ; x, y and z represent a positive number; and n represents zero or a positive integer; calcined products therefrom, and hydrates thereof. The deodorizer may be added thereto independently from or concurrently with other additives to be mixed. 
     Another aspect of the present invention is directed to a process for the preparation of deodorized polyolefins which comprises mixing polyolefins purified by deactivating the catalyst residue remained in crude polyolefins obtained by the polymerization of olefins by use of Ziegler type catalyst at least one deodorizer said above.

This is a continuation of application Ser. No. 450,426, filed 12-16-1982abandoned and the benefits of 35 USC 120 are claimed relative to it.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates to deodorized polyolefins and a process for thepreparation thereof, and more particularly relates to purifiedpolyolefins prepared by deodorizing Ziegler process polyolefins havingoff-odor caused by a catalyst deactivating agent present in the Zieglerprocess polyolefins, and to a process for the preparation of thepurified olefins.

(2) Description of the Prior Art

Recent proposals of the so-called high activity catalyst in the processfor the preparation of polyolefins by use of Ziegler catalyst haveresulted in remarkably simplifying the aforesaid process. Examples ofomitted steps in the aforesaid simplified process compared with theclassic preparation process include an amorphous polyolefin separationstep, a solvent recovery step in the case of a gaseous phase process, adeashing step, and the like. However, even in the case where thedeashing step can be omitted, crude polyolefins resulting immediatelyafter polymerization must be subjected to a purifying step or a catalystdeactivating step prior to being passed, to the following step, becausea catalyst residue contained in the crude polyolefins has some catalyticactivity remaining therein. Examples of the deactivating agent, whichreacts with the catalyst for the deactivation thereof, include water,alcohols, alkylene oxide, and the like. Of these deactivating agents,alkylene oxide is widely used as the deactivating agent due to easinessin handling and to high deactivation effect. However, polyolefinspurified by use of alkylene oxide (hereinafter referred to aspolyolefins purified with alkylene oxide) have such disadvantages thatproducts molded from polyolefins purified with alkylene oxide such asmolded parts, films, fibers and other workpieces have a peculiaroff-odor, which reduces commercial values of the molded products asabove and is liable to make the molded poriducts impossible to be usedfor some applications.

However, the fact that polyolefins purified with alkylene oxide havedisadvantages as above is not publicly known prior to the filing of thispatent application, but has newly been found as the result of studyingdependence of effect on cause between the peculiar off-odor of moldedproducts and the deactivating agent.

With an aim of neutralizing trace amounts of acid substances in thecatalyst residue contained in the polyolefins not purified, for example,Japanese patent laid-open publication No. 3947/1974 discloses a processin which calcium hydroxide or magnesium hydroxide is mixed therewith,and Japanese patent laid-open publication Nos. 49285/1977 and 80447/1980disclose a process in which hydrotalcite is mixed therewith. However,the aforesaid processes are unsatisfactory to solve the problems ofdeodorization described as above.

SUMMARY OF THE INVENTION

An object of the present invention is to provide polyolefins purifiedwith alkylene oxide as the deactivating agent, deodorized and free ofoff-odor when molded therefrom, and a process for the preparationthereof.

Another object of the present invention is to provide deodorized moldedproducts from deodorized polyolefins.

Other object of the present invention is to provide a process for thepreparation of polyolefins, in which application of alkylene oxide asthe deactivating agent in the purifying step is made easier.

An aspect of the present invention is directed to polyolefins deodorizedby mixing polyolefins purified by deactivating the catalyst residueremained in crude polyolefins obtained by the polymerization of olefinsby use of Ziegler type catalyst with 0.001 to 0.5% by weight of at leastone deodorizers selected from the compounds having the followingformulas (1) to (6):

    Al.sub.x Si.sub.y (OH).sub.3x+4y.nH.sub.2 O                (1)

    Mg.sub.x (OH).sub.2y-2x (CO.sub.3).sub.y.nH.sub.2 O        (2)

    Mg.sub.x Ca.sub.y (CO.sub.3).sub.2x+2y/2.nH.sub.2 O        (3)

    M.sub.x Si.sub.y (OH).sub.2x+4y.nH.sub.2 O                 (4)

    M.sub.x Al.sub.y Si.sub.z (OH).sub.2x+3y+4z.nH.sub.2 O     (5)

    M.sub.x Al.sub.y (OH).sub.2x+3y-2z (A).nH.sub.2 O          (6)

where M represents Mg or Ca; A represents CO₃, HOP₄ or SO₄ ; x, y and zrepresent a positive number; and n represents zero or a positiveinteger; calcined products therefrom, and hydrates thereof.

Another aspect of the present invention is directed to a process for thepreparation of deodorized polyolefins which comprises mixing polyolefinspurified by deactivating the catalyst residue remained in crudepolyolefins obtained by the polymerization of olefins by use of Zieglertype catalyst with 0.001 to 0.5% by weight of at least one deodorizersselected from the compounds having the following formulas (1) to (6):

    Al.sub.x Si.sub.y (OH).sub.3x+4y.nH.sub.2 O                (1)

    Mg.sub.x (OH).sub.2y-2x (CO.sub.3).sub.y.nH.sub.2 O        (2)

    Mg.sub.x Ca.sub.y (CO.sub.3).sub.2x+2y/2.nH.sub.2 O        (3)

    M.sub.x Si.sub.y (OH).sub.2x+4y.nH.sub.2 O                 (4)

    M.sub.x Al.sub.y Si.sub.z (OH).sub.2x+3y+4z.nH.sub.2 O     (5)

    M.sub.x Al.sub.y (OH).sub.2x+3y-2z (A).nH.sub.2 O          (6)

where M represents Mg or Ca; A represents CO₃, HPO₄ or SO₄ ; x, y and zrepresent a positive number; and n represents zero or a positiveinteger; calcined products therefrom, and hydrates thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Olefins used in the present invention include those substantially usedas the starting material for the preparation of polyolefins. Examples ofthe olefins used in the present invention include mono-α-olefins such asethylene, propylene, butene-1, 4-methyl pentene-1 and hexene-1, cyclicvinyl compounds such as stylene and vinyl cyclohexane, diolefins such asbutadiene, and the like.

Ziegler type catalyst used in the present invention is typically knownas a combination of organometallic compounds of the metals of Groups Ito III of the Periodic Table with transition metal compounds (includingthose having less valency than the maximum valency) or as improvementsthereof. Furthermore, Ziegler type catalyst includes those havingvarious third ingredients or with transition metal compound supported ona carrier for the purpose of improving catalyst performance, and thosewith which α-olefins are prepolymerized, to enhance invention is mixedwith a predetermined amount of a deodorizer selected from inorganicdouble salts with water of crystallization as represented by theformulas (1) to (6):

    Al.sub.x Si.sub.y (OH).sub.3x+4y.nH.sub.2 O                (1)

    Mg.sub.x (OH).sub.2y-2x (CO.sub.3).sub.y.nH.sub.2 O        (2)

    Mg.sub.x Ca.sub.y (CO.sub.3).sub.2x+2y/2.nH.sub.2 O        (3)

    M.sub.x Si.sub.y (OH).sub.2x+4y.nH.sub.2 O                 (4)

    M.sub.x Al.sub.y Si.sub.z (OH).sub.2x+3y+4z.nH.sub.2 O     (5)

    M.sub.x Al.sub.y (OH).sub.2x+3y-2z (A).nH.sub.2 O          (6)

where M represents Mg or Ca, A represents CO₃, HPO₄ or SO₄ ; x, y and zrepresent a positive number, and n represents zero or a positive number;calcined products thereof; and hydrates thereof.

The calcined product as above is obtained by heating the double salts toremove partly or completely moisture or water of crystallizationcontained therein for dehydration. The inorganic double saltsrepresented by the formulas (1) to (6) as above, calcined productsthereof, or hydrates thereof (hereinafter may be referred to asinorganic salts, etc. of the present invention) have a mean particlesize less than 10 μm, preferably 0.01 to 1 μm. The inorganic doublesalts, etc. having a particle size less than 0.01 μm may be used so longas uniform mixing can be performed. The specific surface of particles ofthe inorganic double salts, etc. used in the present invention is notspecifically limited, the greater the better, preferably 10 to 300 m²/g. The inorganic double salts, etc. of the present invention are mixedwith the polyolefins purified as above in an amount of from 0.001 to0.5% by weight, preferably 0.005 to 0.1% by weight thereof based on theweight of the polyolefins purified as above. As apparent from thepercentage of the amount of the inorganic double salts, etc. to bemixed, the amount of the inorganic double salts, etc. to be mixed issubstantially much less than those of other additives such as heatstabilizers. To be surprised, addition of such an extremely small amountof the inorganic double salts, etc. makes possible to sufficientlydeodorize the purified polyolefins having off-odor, which is remarkablyincreased for molded products. The mixing method of the inorganic doublesalts, etc. of the present invention with the purified polyolefins, etc.is not specifically limited, so long as uniform mixing is performed inspite of such a small amount of the inorganic double salts, etc. to bemixed.

The inorganic double salts, etc. may be mixed with the purifiedpolyolefin prior to addition of other additives, concurrently with otheradditives, or after addition of other additives, that is, in theplastisizing step in the pelletization of the purified polyolefin. Theinorganic double salts, etc. are added in such a small amount that theinorganic double salts, etc. are preferably mixed beforehand with asmall amount of the purified polyolefin powder to obtain a mixedproduct, which is then mixed with the purified polyolefin. Mixingapparatuses and mixing conditions are not specifically limited, butmixing of the inorganic double salts, etc. with the purified polyolefinis generally conducted by use of a high speed agitation type mixer orHenschell mixer, a trade name, at a temperature of from room temperatureto 50° C. for a period of one minute to 30 minutes. Other mixing devicessuch as a ribbon blender or twin-shell blender may also be used.

The deodorized polyolefin of the present invention is processed tomolded parts, films, fibers, and other molded products with little or nopeculiar off-odor caused by the alkylene oxide, resulting in releasingany restrictions in application thereof such as non-availability thereofto food containers, and in preventing reduction in commercial values ofmolded products due to off-odor.

The process of the present invention may be said a much more preferableprocess for the preparation of deodorized polyolefins compared withother provable deodorizing processes such as a process in whichingredients having off-odor are extracted with solvent from purifiedpolyolefins as above in that the process of the present invention isreadily applicable without needing any additional apparatus or anyaddition method to the conventional process of pelletization from thepurified polyolefin as above, and without impairing any additionprocesses of other additives.

The present invention will be explained more in detail by the followingexamples and comparative examples.

In the examples and comparative examples, measurements are made asfollows:

MFR is measured according to ASTM-D1738.

With respect to ash content in polyolefin, the amounts of Al, Ti and Clare measured by fluorescent X-ray analysis as shown by XRFCl. The amountof active chlorine is measured in such a manner that a sample ofpolyolefin is heated to 300° C., to measure an amount of hydrogenchloride in the gas thus generated, and the amount of hydrogen chlorideis represented by a proportion thereof to polyolefin. Yellowness Index(YI) is measured by a differential colorimeter (marketed by Suga TesterCo., Ltd.).

The off-odor of the molded product is classified into the following fivegrades 1, 2, 3, 4 and 5:

1 represents "strongly smelling",

2 represents "considerably smelling",

3 represents "smelling",

4 represents "a little smelling", and

5 represents "non-smelling",

according to the results of an organoleptic test of test pieces justremoved from the molding machine, which applies to additives (compoundsor calcined products thereof) used in the examples and comparativeexamples as shown in Table-1.

                                      TABLE 1                                     __________________________________________________________________________    Additives                        Particle                                     No.                                                                              Type*                                                                             Names of additives                                                                          Formulas of additives                                                                     sizes                                        __________________________________________________________________________    1  --  α-alumina                                                                             Al.sub.2 O.sub.3                                                                          ≦3μ                                2  --  ultrafine silica                                                                            SiO.sub.2   ≦0.05μ                             3  --  magnesia      MgO         mean 10μ                                  4  (4) talc**        Mg.sub.3 Si.sub.4 O.sub.10 (OH).sub.2                                                     ≦1μ                                5  (1) aluminium silicate**                                                                        Al.sub.2 O.sub.3.2SiO.sub.2                                                               ≦1μ                                6  (3) magnesium calcium silicate**                                                                CaMg(CO.sub.3).sub.2                                                                      ≦1μ                                7  (2) basic magnesium carbonate                                                                   4MgCO.sub.3.Mg(OH).sub.2.4H.sub.2 O                                                       ≦1μ                                8  (5) magnesium aluminosilicate**                                                                 MgO.Al.sub.2 O.sub.3.2SiO.sub.2                                                           ≦1μ                                9  (6) hydrotalcite  Mg.sub.4.Al.sub.2 (OH).sub.2 CO.sub.3.3H.sub.2                                            ≦0.5μ                              10 (6) hydrotalcite**                                                                              Mg.sub.4.Al.sub.2 (OH).sub.2 CO.sub.3                                                     ≦0.5μ                              11 (5) calcium aluminosilicate**                                                                   CaO.Al.sub.2 O.sub.3.2SiO.sub.2.4H.sub.2 O                                                1-5μ                                      __________________________________________________________________________     Note: *(1) to (6) represent the deodorizers used in the present invention     **calcined products thereof respectively                                 

EXAMPLES 1-8; COMPARATIVE EXAMPLES 1-3

The purified polypropylene used in the present invention is prepared inthe following manner. A 860 l horizontal polymerizer fitted with astirrer, a number of rotation of which is 40 rpm, and having a L/D of 5is dried and the air therein is replaced by nitrogen gas. Into apolypropylene powder bed in the polymerizer, 17.3 g/Hr of titaniumtrichloride composition as a catalyst as described in Example 1(1) ofJapanese Patent Application No. 12875/1980, 40 g/Hr of diethyl aluminumchloride, propylene as the starting material, and hydrogen as amolecular weight modifier at a gaseous concentration of 2.0 mol % arecharged to be subjected to gas phase polymerization for 3 hours at atemperature of 70° C. under a pressure of 20 Kg/cm² G, followed byreplacement of nitrogen therein by air and cooling to obtain crudepolypropylene having a MFR of 7.0, and containing 34 ppm of Ti, 60 ppmof Al, and 150 ppm of Cl resulting from the catalyst used respectively.The crude polypropylene powder is purified in the following manner. Thecrude polypropylene charged in a fluidized bed purifying apparatus arefluidized with a fluidizing and purifying gas composed of one mol % ofpropylene oxide and 99 mol % of nitrogen at 95° C. for 30 minutes todeactivate the catalyst residue contained in the crude polypropylene,resulting in obtaining purified polypropylene.

Procedures of respective examples and comparative examples are carriedout by use of the purified polypropylene in the following manner. 10 Kgof the purified polypropylene, 0.01 Kg of2,6-di-tertiary-butyl-4-methylphenol, 0.01 Kg of calcium stearate andrespective additives listed in Table-1 are mixed in a high speedagitation type mixer (Henschel mixer) at room temperature for 10minutes. The resulting mixture is subjected to pelletization by use oftwin granulator at 230° C. The pellets thus obtained are molded by useof an injection molding machine to form a test piece of 150 mm×150 mm×3mm.

Effects on the YI and grades of smelling of the types and amounts ofadditives are shown in Table-2.

                  TABLE 2                                                         ______________________________________                                                  Additives                                                                          Amounts    Effects                                                            (% by      YI of   Grade of                                              No.  weight)    pellet  off-odor                                    ______________________________________                                        Example 1   9      0.01       1.5   4                                         Example 2   4      0.01       1.6   4                                         Example 3   5      0.02       1.4   4                                         Example 4   6      0.03       1.3   4                                         Example 5   7      0.04       1.2   4                                         Example 6   8      0.03       1.5   4                                         Example 7   9      0.05       1.6   5                                         Example 8   10      0.007     1.4   5                                         Example 9   11     0.01       1.0   5                                         Comparative none   --         1.7   1                                         Example 1                                                                     Comparative 1      0.01       1.7   1                                         Example 2                                                                     Comparative 2      0.01       2.0   2                                         Example 3                                                                     ______________________________________                                         Note: The ash content of each pellet is 12 ppm in terms of XRFCl.        

Each pellet has an active chlorine content in the purified polypropyleneof zero ppm.

What is claimed is:
 1. Deodorized polypropylenes comprising a mixtureof(a) polypropylenes that have been produced with a Ziegler catalyst andwhich have had the catalyst deactivated with an alkylene oxide andcontaining zero active chlorine, and (b) 0.005 to 0.1% by weight of atleast one deodorizer selected from the compounds having the followingformula 1 to 6:

    Al.sub.x Si.sub.y (OH).sub.3x+4y. nH.sub.2 O               (1)

    Mg.sub.x (OH).sub.2y-2x (CO.sub.3).sub.y.nH.sub.2 O        (2)

    Mg.sub.x Ca.sub.y (CO.sub.3).sub.2x+2y/2.nH.sub.2 O        (3)

    M.sub.x Si.sub.y (OH).sub.2x+4y.nH.sub.2 O                 (4)

    M.sub.x Al.sub.y Si.sub.z (OH).sub.2x+3y+4z.nH.sub.2 O     (5)

    M.sub.x Al.sub.y (OH).sub.2x+3y-2z (A).nH.sub.2 O          (6)

where M represents Mg or Ca; A represents CO₃, HPO₄ or SO₄ ; x, y and zrepresent a positive number; and n represents zero or a positiveinteger;as well as calcined products and hydrates thereof.
 2. A methodfor deodorizing off-odor polypropylenes which comprises incorporating0.005 to 0.1% by weight of at least one deodorizer compound in saidoff-odor polypropylenes(a) said off-odor polypropylenes comprisingolefins polymerized with a Ziegler-type catalyst and treated with analkylene oxide to deactivate the Ziegler-type catalyst at the end of thepolymerization, and containing zero active chlorine, (b) said deodorizercompound being selected from the group consisting of

    Al.sub.x Si.sub.y (OH).sub.3x+4y.nH.sub.2 O                (1)

    Mg.sub.x (OH).sub.2y-2x (CO.sub.3).sub.y.nH.sub.2 O        (2)

    Mg.sub.x Ca.sub.y (CO.sub.3).sub.2x+2y/2.nH.sub.2 O        (3)

    M.sub.x Si.sub.y (OH).sub.2x+4y.nH.sub.2 O                 (4)

    M.sub.x Al.sub.y Si.sub.z (OH).sub.2x+3y+4z.nH.sub.2 O     (5)

    M.sub.x Al.sub.Y (OH).sub.2x+3y-2z (A).nH.sub.2 O          (6)

where M represents Mg or Ca; A represents CO₃, HPO₄ or SO₄ ; x, y and zrepresent a positive number; and n represents zero or a positiveinteger;as well as calcined products and hydrates thereof.
 3. A methodaccording to claim 2 wherein said deodorizer compound is Al_(x) Si_(y)(OH)_(3x+4y).nH₂ O.
 4. A method according to claim 2 wherein saiddeodorizer compound is Mg_(x) (OH)_(2y-2x) (CO₃)_(y).nH₂ O.
 5. A methodaccording to claim 2 wherein said deodorizer compound is Mg_(x) Ca_(y)(CO₃)_(2x+2y/2).nH₂ O.
 6. A method according to claim 2 wherein saiddeodorizer compound is M_(x) Si_(y) (OH)_(2x+4y).nH₂ O.
 7. A methodaccording to claim 2 wherein said deodorizer compound is M_(x) Al_(y)Si_(z) (OH)_(2x+3y+4z).nH₂ O.
 8. A method according to claim 2 whereinsaid deodorizer compound is M_(x) Al_(y) (OH)_(2x+3y-2z) (A).nH₂ O.